1. Technical Field
The present invention relates generally to audio content and more specifically to transmission of audio content. Still more particularly, the present invention relates to selection of an optimized codec for audio content.
2. Description of the Related Art
Technology for transmission of audio content in conventional media (e.g., radio and television) is known in the art. In addition to these conventional media, transmission of audio content via the Internet is quickly growing in popularity. With each conventional media, audio transmission is constrained by two key variables/parameters: (1) available bandwidth; and (2) quality of encoding/decoding (codec) processing. Selected codec is often influenced by the desire to minimize the bandwidth required for transmission while maximizing the quality of the transmitted content.
Available bandwidth is typically a static quantity, and codecs are designed to transmit content within pre-set maximum bandwidths. Thus, for the most part, codec quality differentiates the transmission and is the primary consideration influencing the types of devices (encoders, decoders, transmitters, etc.) and processes utilized at the broadcasting and receiving ends of the transmission. Codec is itself constrained by the type/makeup of content being transmitted. In audio content, for example, there are two distinct types of data signals, traditional voice signal (human voices) and non-voice signals, such as music/musical instruments, etc. While it is likely that audio content may consists primarily of one type of signal, it is quite common for audio content to include both types of signals within a single audio stream. Notably, from a codec analysis, each signal type has distinct characteristics/qualities that respond better to specific codec processing. Also, codec processing utilized for voice signals may not be appropriate (i.e., less ideal) for non-voice signals.
Thus, several different types of audio encoders and decoders have been created, some of which are designed to support a preferred type of audio content. One commonly utilized group of codec devices are the “Ogg” family of encoders and decoders (within the Ogg container). The Ogg container is able to encapsulate arbitrary audio codecs. The “Ogg Vorbis” audio codec performs well and is commonly utilized for general purpose audio content, including both voice and music. Features of Ogg Vorbis codec are described at world-wide web site “xiph.org/ogg/vorbis/”. “Ogg Speex”, in contrast, is optimized for the human voice alone and does not perform well for general purpose audio content. When encoding only voice content, Ogg Speex codec provides the best codec processing from a quality and bandwidth standpoint. Ogg Speex codec is described at world-wide web site “speex.org”.
Conventional audio broadcast solutions constrains the broadcaster to only one codec per broadcast stream, even though different audio codecs perform better for different types of audio content. When selecting an audio codec for the content to be streamed over the Internet, radio stations that broadcast both talk programs and music currently select the most general purpose codec (e.g., Ogg Vorbis codec). As a result, both music and voice content is brought to a lowest common denominator of quality.